1. Field of the Invention
The present invention is related generally to a fluid supply system and, more specifically, to a dual fuel tank system for use in conjunction with portable engine driven equipment such as a portable compressor.
2. Description of the Prior Art
When portable engine driven equipment is used, one recurring problem relates to the fuel supply system that provides for a flow of fuel from a storage tank to an internal combustion engine. When the portable equipment is parked on terrain which is not level, the fuel will be caused to flow toward one side of the fuel tank. If the fuel pickup conduit is located at an opposite end of the tank, the engine could be deprived of fuel prior to the depletion of all of the fuel that is stored in the tank.
In order to expand the total capacity of fuel stored in a portable engine driven apparatus, it is known that two fuel tanks can be used. An advantage of using two fuel tanks, rather than one very large fuel tank, is that it permits the location of these tanks to be placed at convenient positions on the apparatus. However, if the device is parked on unlevel ground, both fuel tanks could be tilted in such a way that the fuel pickup conduit is not disposed within the fuel even though additional liquid fuel is available within the two storage tanks. Although it is known to use two fuel tanks in a portable apparatus, usually only one of the two fuel tanks is provided with a fuel pickup conduit. Most typically, the other fuel tank is provided with a return line from the fuel system of the engine. Therefore, even if the two fuel tanks are connected in fluid communication with each other, all of the fuel can be caused to move away from the fuel pickup conduit when the vehicle is parked on unlevel ground. Therefore, the mere use of two fuel tanks does not solve the problem described above.
U.S. Pat. No. 4,715,345, which issued to Reames, Jr. on Dec. 29, 1987, discloses an automatic fuel shutoff system for fuel injected engines. It provides an assembly which is positioned between a main fuel supply and a fuel injection system of a fuel injected gasoline engine or diesel engine. When the main fuel supply becomes exhausted, the fuel flow to the fuel injection system is automatically shut off, causing the engine to cease operating because of fuel starvation. This prevents air from entering the fuel injection system. The assembly described in this patent forms a reserve supply of fuel and utilizes the vacuum created by the fuel starved engine in such a way as to insure that no air becomes entrained in the fuel injection system when operation of the system is resumed following the replenishment of the fuel supply.
U.S. Pat. No. 4,763,633, which issued to Nakanishi on Aug. 16, 1988, describes a fuel supply system for a small boat in which the fuel supply system comprises a suction pipe which has an inlet opening within a fuel tank. A fuel retention device is connected to the pipe around the inlet opening and it retains fuel at the inlet opening to prevent air from entering the opening when the opening is above the fuel level for a brief period of time.
U.S. Pat. No. 2,320,913, which issued to Crowell on June 1, 1943, describes a liquid fuel or lubricant supply tank. This patent describes a fuel tank which contains a plurality of compartments that are all connected in fluid communication with each other. A piping arrangement is provided to connect each of the compartments to each of the other compartments for the purpose of permitting fuel to flow freely between associated compartments of the main fuel tank. If one of the compartments is emptied, such as would result from a piercing of the wall of one of the compartments, a device attached to the ends of the piping prevents fuel from flowing from one of the other compartments into that emptied compartment.
U.S. Pat. No. 4,411,239, which issued to Kelch on Oct. 25, 1983, describes a fuel cooling system for use with a closed fuel injection circuit in a diesel engine. Although this patent describes a device which is not directly related to the present invention, it does illustrate an example where a fuel tank is provided with two fuel pickup conduits. The cooling system for the fuel used in a diesel engine, according to this patent, includes a closed fuel injection circuit and a fuel cooling circuit. The fuel cooling circuit flows fuel to and from the fuel tank. A heat exchanger is connected to a fuel injection circuit and the fuel cooling circuit and flows the fuel from the fuel injection circuit in indirect heat transfer relation with the fuel in the cooling circuit for removing heat from the fuel in the injection circuit.
U.S. Pat. No. 3,101,771, which issued to McCuen on Aug. 27, 1963, discloses a liquid fuel system for vehicles. It describes a system which contains two fuel tanks wherein each fuel tank is provided with a single fuel pickup conduit and a single fuel return conduit. A separate containment is also provided for an intermediate storage of fuel between the main storage tanks and the carburetor of the vehicle. Fuel is pumped from the two main storage tanks into the intermediate tank and overflowing fuel is returned from the intermediate tank back to the main storage tanks. The pickup conduits and the return conduits are each provided with valves for selectively opening and closing these conduits.
U.S. Pat. No. 3,530,876, which issued to Stoner on Sept. 29, 1970, describes a control valve for a brine tank of a water softener system. It describes an apparatus for controlling the liquid into and out of the brine tank. A conduit through which fresh water is admitted to the tank and brine is withdrawn from the tank ends in a valve plug placed substantially above the tank bottom. The valve comprises a vertically elongated, vertically movable valve chamber which surrounds the valve plug and has top and bottom valve seats which cooperate with the plug to shut off liquid flow through the pipe. The chamber has a float to cause it to rise and fall with the level in the brine tank. The chamber has an opening near its bottom in communication with the liquid in the tank.